Multi-stage transmission

ABSTRACT

A multi-stage transmission comprising two planetary gear sets (RS 2 , RS 3 ) and one planetary reduction gear set (VS), one first clutch (A) and one second clutch (B), one third clutch (E) and one first brake (C), one second brake (D), the external disc carrier of the clutch (B) being connected with one output element of the planetary reduction gear set (VS), the internal disc carrier of the clutch (B) leads to the internal disc carrier of the brake (C) which is connected with one element of the planetary gear set (RS 2 ), the internal disc carrier of the clutch (A) being connected with one output element of the planetary reduction gear set (VS) and the external disc carrier of the clutch (A) with one element of the planetary gear set (RS 3 ), the external disc carrier of the clutch (E) being connected with one input element of the planetary reduction gear set (VS) and with the drive shaft (AN), the internal disc carrier of the clutch (E) being connected respectively with one element of the planetary gear set (RS 2 ) and of the planetary gear set (RS 3 ), the brake (D) being connected with the planetary gear set (RS 2 ) and the housing being connected with one supporting element of the planetary reduction gear set (VS) and the driven shaft (AB) with the planetary gear set (RS 2 ).

This application is a national stage completion of PCT/EP03/02194 filedMar. 4, 2003 which claims priority from German Application Serial No.102 10 348.8 filed Mar. 8, 2002.

FIELD OF THE INVENTION

The invention relates to a multi-stage transmission in planetary design,particularly an automatic transmission for a motor vehicle.

BACKGROUND OF THE INVENTION

In the automatic transmission prior art, particularly for motorvehicles, transmissions comprise planetary gear sets which are shiftedby means of friction or shifting elements, such as clutches and brakes,and are usually connected with a starting element, such as ahydrodynamic torque converter or a fluid clutch, subject to a slipeffect and optionally provided with a lock-up clutch.

Such a transmission results from EP 0 434 525 A1. It essentiallycomprises one drive shaft and one driven shaft disposed parallel witheach other, one double planetary gear set disposed concentrically to thedriven shaft and five shifting elements in the form of three clutchesand two brakes, the optional locking of which by pairs determines thedifferent gear ratios between the drive shaft and the driven shaft. Thistransmission has one planetary reduction gear set and two power paths sothat by selective engagement by pairs of the five shifting elements sixforward gears are obtained.

In the first power path are needed two clutches for transmitting thetorque from the planetary reduction gear set to two elements of thedouble planetary gear set. These are disposed, axially observed,essentially behind the reduction gear set in direction of the doubleplanetary gear set. In the second power path is provided one otherclutch which loosely connects it with one other element of the doubleplanetary gear set. The clutches are arranged here in a manner such thatthe internal disc carrier constitutes the output.

From the published U.S. Pat. No. 6,139,463 is further known amulti-stage transmission in planetary design, specially for a motorvehicle, which has two planetary gear sets and one planetary reductiongear set, the same as three clutches and two brakes. In this alreadyknown multi-stage transmission, two clutches C-1 and C-3 are provided inthe first power path for transmitting the torque from the planetaryreduction gear set to the two planetary gear sets. The external disccarrier or the cylinder or piston and pressure compensation side of theclutch C-3 is connected with a first brake B-1. Besides, the internaldisc carrier of the third clutch C-3 is connected with the cylinder orpiston and pressure compensation side of the first clutch C-1, theinternal disc carrier of the first clutch C-1 being situated on theoutput side and connected with a sun gear of the third planetary gearset.

The known multi-stage transmission has the disadvantage that,particularly in the sixth gear, the first brake B-1 is closed. Therebystands the cylinder of the third clutch C-3 so that no hydrodynamicpressure can build up. In this manner, the pressure compensation spaceof the third clutch can run idle whereby the shifting quality of theknown multi-stage transmission is impaired.

From the published U.S. Pat. No. 6,135,912 is further known a similarmulti-stage transmission. In this multi-stage transmission which,likewise, has two clutches C-1 and C-3 for transmitting the torque fromthe planetary reduction gear set to the planetary gear sets, theinternal disc carriers of these clutches are preferably connected withthe planetary gear sets. One other embodiment disclosed within the scopeof the cited publication provides that the external disc carrier of theclutch C-3 is situated on the output side. This construction, speciallythe arrangement of the clutches relative to the output or input, hasalso been disclosed within the scope of U.S. Pat. No. 6,120,410 whichalso describes a multi-stage transmission of the type mentioned.

The problem on which this invention is based is to propose a multi-stagetransmission of the above mentioned type in which the shifting qualityis improved. A clutch system is to be specially indicated which, incompact design, makes it possible to implement a quick and comfortableshifting behavior.

SUMMARY OF THE INVENTION

An inventive multi-stage transmission in planetary design with two powerpaths is accordingly proposed in which a first and a second clutch areprovided for transmitting the torque of the planetary reduction gear setto the two planetary gear sets of a main gear set via a first powerpath. The second clutch is here connectable on the output side with onebrake whereas the output side of the first clutch is connected with oneelement of the main gear set.

Contrary to the prior art, the external disc carrier of the secondclutch connectable on the output side with a first brake is tied to arotating output element of the planetary reduction gear set thuspreventing an idling operation of a preferably existing pressurecompensation space. The internal disc carrier of this second clutchpreferably leads, when radially observed, above the first clutch to theinternal disc carrier of the first brake which is connected via oneshift with one element of the second planetary gear set. The internaldisc carrier of the first clutch is inventively tied directly to theoutput or to the output element of the planetary reduction gear set, theexternal disc carrier or the cylinder/piston side of the first clutchbeing connected via one shaft with one element of the third planetarygear set.

It is further provided in the inventive multi-stage transmission thatthe external disc carrier of a third clutch provided for the secondpower path is connected with an input element of the planetary reductiongear set and with the drive shaft, the internal disc carrier of thethird clutch being connected, respectively, with one element of thesecond planetary gear set and of the third planetary gear set. Onesecond brake is also connected with an element of the second planetarygear set. In addition, the housing is connected with one supportingelement of the planetary reduction gear set and the driven shaft isconnected with one element of the second planetary gear set.

In this manner the positions, particularly of the first clutch and ofthe second clutch, are changed compared to the prior art. Thereby areprevented disadvantages known from the prior art, specially from U.S.Pat. No. 6,139,463, so that in the inventive multi-stage transmissionthe shifting quality is advantageously improved.

According to a development of this invention, the ring gear can beprovided as input element of the planetary reduction gear set. It isalso conceivable that in the inventive multi-stage transmission, thespider or any other central gear is used as planetary reduction gearset.

Within the scope of another development of the invention, the spider canbe provided as an output element of the planetary reduction gear set. Itis also conceivable here that a central gear is provided, as needed, inthe inventive multi-stage transmission.

It is also possible that in the inventive multi-stage transmission, thesun gear is provided as supporting element of the planetary reductiongear set. But it is also possible that the spider or any other centralgear ise used as a supporting element.

It is especially advantageous if the second planetary gear set and thethird planetary gear set are designed as so-called Ravigneaux gear sets.

Within the scope of one embodiment of the invention it is proposed tosituate the planetary reduction gear set, radially observed, essentiallybeneath the second clutch whereby a specially compact construction isimplemented. In this connection, the third clutch can be located,radially observed, essentially beneath the first clutch.

In the inventive multi-stage transmission, six forward gears and onereverse gear are preferably implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with referenceto the accompanying drawings in which:

FIG. 1 is a cut partial view of an inventive multi-stage transmission;

FIG. 2 is a principle shift pattern of the inventive multi-stagetransmission; and

FIG. 3 is a circuit diagram of the inventive multi-stage transmissionaccording to FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 and 2 is shown an inventive multi-stage transmission inplanetary design, particularly an automatic transmission for a motorvehicle. The inventive multi-stage transmission comprises at least onedrive shaft AN and one driven shaft AB located in one housing. Inaddition, one first gear set, one planetary reduction gear set VS andone main gear set with one second and one third planetary gear set RS2,RS3 are provided. The second planetary gear set RS2 and the thirdplanetary gear set RS3, in the development shown of the inventivemulti-stage transmission, are designed as Ravigneaux gear sets.

In the multi-stage transmission are further provided five shiftingelements, namely, one first clutch A, one second clutch B and one thirdclutch E and one first brake C and one second brake D, the clutches Aand B transmitting the torque of the planetary reduction gear set to theplanetary gear sets RS2, RS3 of the main gear set. By means of aselective engagement by pairs, the shifting elements produce differentreduction ratios between the drive shaft AN and the driven shaft AB sothat six forward gears and one reverse gear can preferably beimplemented.

It is inventively provided in the multi-stage transmission that theexternal disc carrier or the cylinder, piston and pressure compensationside of the clutch B is connected with a spider St1 of the planetaryreduction gear set VS. At least the clutch B preferably has one servodevice with one dynamic pressure compensation. The inventive ideaprevents an idling of the pressure compensation spaces thus improvingthe comfort and shifting quality. The internal disc carrier of theclutch B, preferably radially observed, leads here above the clutch A tothe internal disc carrier of the brake C which is fastened on thehousing. The internal disc carrier of the brake C is connected via oneshaft with a sun gear S2 of the second planetary gear set RS2 designedas a Ravigneaux gear set. The internal disc carrier of the clutch A issituated on the input side and directly tied to the spider St1 of theplanetary reduction gear set, the external disc carrier or the cylinderor piston and pressure compensation side of the clutch A being connectedvia one shaft with a sun gear S3 of the third planetary gear set RS3designed as a Ravigneaux gear set.

The external disc carrier or the cylinder or piston and pressurecompensation side of the clutch E is connected with a ring gear H1 ofthe planetary reduction gear set VS and with the drive shaft AN. Theinternal disc carrier of the clutch E is connected respectively with aspider St2 of the second planetary gear set RS2 and with a spider St3 ofthe third planetary gear set RS3. Besides, the brake D, which isconnected with the housing, is tied by its internal disc carrier to thespider St2 of the second planetary gear set RS2. A sun gear S1 isconnected with the housing as supporting element of the planetaryreduction gear set VS. In addition, a ring gear H2 is connected with thedriven shaft AB.

In the inventive multi-stage transmission, the shifting quality can beadvantageously improved by the arrangement of the input of the clutch Aas internal disc carrier and of the input of the clutch B as an externaldisc carrier. Besides, in this development of the instant invention, thetransmission input rotational speed detection can be left on the formerplace.

In FIGS. 1 and 2, the planetary reduction gear set VS, radiallyobserved, is essentially beneath the second clutch B and the thirdclutch E essentially beneath the first clutch A whereby a speciallycompact design is obtained.

The corresponding wiring diagram of the embodiment of the inventivemulti-stage transmission is shown in FIG. 3, there being indicated byway of example ratios i and a resulting ratio steps φ.

Accordingly, the inventive multi-stage transmission has a progressivegradation. Besides, double shifts are prevented in sequential shiftingmode, since each of the adjacent gear steps uses one shifting element incommon. IN addition, only one shifting element is actuated in any gearshift between the first and the fourth gears and between the fifth andthe sixth gears.

For the gears 1 to 4, the clutch A is permanently activated.Additionally, the brake D is closed or actuated in the first gear; thebrake C, in the second gear; the brake B, in the third gear; and theclutch E, in the fourth gear. In the gears 5 and 6, together with thepermanently actuated clutch E, additionally, the clutch B is activatedin the fifth gear and the clutch C, and in the sixth gear. In thereverse gear, the clutch B and the brake D are activated.

Reference numerals A first clutch B second clutch E third clutch C Firstbrake D second brake VS planetary reduction gear set RS2 secondplanetary gear set RS3 third planetary gear set AN drive shaft AB drivenshaft S1 sun gear of the planetary reduction gear set S3 sun gear of thesecond planetary gear set S3 sun gear of the third planetary gear setSt1 spider of the planetary reduction gear set St2 spider of the secondplanetary gear set St3 spider of the third planetary gear set H1 ringgear of the planetary reduction gear set H2 ring gear of the secondplanetary gear set i ratio φ ratio steps 1 gear 2 gear 3 gear 4 gear 5gear 6 gear

1. A multi-stage automatic transmission of a planetary design for amotor vehicle, comprising: at least one drive shaft (AN) and one drivenshaft (AB) located in a housing; at least two planetary gear sets (RS2,RS3) of a main gear set and one planetary reduction gear set (VS), atleast five shifting elements comprising a first clutch (A) and a secondclutch (B) which transmit torque of the planetary reduction gear set viaa first power path to the planetary gear sets (RS2, RS3) of the maingear set, a third clutch (E) and a first brake (C) and a second brake(D) for selective engagement of pair of the shifting elements to producedifferent reduction ratios between the drive shaft and the driven shaft,wherein an external disc carrier of the second clutch (B) is connectedwith one output element of the planetary reduction gear set (VS), aninternal disc carrrier of the second clutch (B) extends radially abovethe first clutch (A) to the internal chisc carrier of the first brake(C), and the first clutch (A) is axially positioned between the secondclutch (B) and the first brake (C), an internal disc carrier of thesecond clutch (B) extends to an internal disc carrier of the first brake(C) which, via a first shaft, is connected with one element of a secondplanetary gear set (RS2), an internal disc carrier of the first clutch(A) is connected with one output element of the planetary reduction gearset (VS), an external disc carrier of the first clutch (A) is connectedwith (VS) element of a third planetary gear set (RS3), an external disccarrier of the third dutch (E) is connected with one input element ofthe planetary reduction gear set (VS) and with the drive shaft (AN), theinternal disc carrier of the third clutch (E) is respectively connectedwith one element of the second planetary gear set (RS2) and of the thirdplanetary gear set (RS3), the second brake (D) is connected with oneelement of the second planetary gear set (RS2), the housing is connectedwith one supporting element of the planetary reduction gear set (VS) andthe driven shaft (AB) is connected with one element of the secondplanetary gear set (RS2).
 2. The multi-stage transmission according toclaim 1, wherein the planetary reduction gear set (VS), observedradially, is substantially situated beneath the second clutch (B). 3.The multi-stage transmission according to claim 1, wherein that thethird clutch (E), observed radially, is substantially situated beneaththe first clutch (A).
 4. The multi-stage transmission according to claim1, wherein at least the second clutch (B) has one serve device with adynamic pressure compensation.
 5. The multi-stage transmission accordingto claim 1, wherein a first ring gear (H1) is provided as an inputelement of the planetary reduction gear set (VS).
 6. The multi-stagetransmission according to claim 1, wherein a first spider (St1) isprovided as an output element of the planetary reduction gear set (VS).7. The multi-stage transmission according to claim 1, wherein a firstsun gear (S1), which is connected with the housing, is provided as asupporting element of the planetary reduction gear set (VS).
 8. Themulti-stage transmission according to claim 1, wherein the secondplanetary gear set (RS2) and the third planetary gear set (RS3) are bothdesigned Ravigneaux gear sets.
 9. The multi-stage transmission accordingto claim 1, wherein the multi-stage transmission can implement sixforward gears and one reverse gear.
 10. A multi-stage automatictransmission for a motor vehicle, comprising: at least one drive shaft(AN) and one driven shaft (AB) located in a housing; one planetary gearset (VS); at least a first planetary gear set (RS2) and a secondplanetary gear set (RS3) of a main gear set; at least five shiftingelements comprising; a first clutch (A) and a second clutch (B) whichtransmit torque of the planetary reduction gear set via a first powerpath to the first planetary gear set (RS2) and the second planetary gearset (RS3) of the main gear set; a third clutch (E), a first brake (C)and a second brake (D) for selective engagement of pairs of the shiftingelements to produce different reduction ratios between the drive shaftand the driven shaft; and wherein an external disc carrier of the secondclutch (B) is connected with one output element of the planetaryreduction gear set (VS), an internal disc carrier of the second clutch(B) extends radially beyond the first clutch (A) to an internal disccarrier of the first brake (C) which, via a first shaft, is connectedwith one element of the second planetary gear set (RS2), and the firstclutch (A) is positioned axially in the transmission between the secondclutch (B) and the first brake, and an internal disc carrier of thefirst clutch (A) is connected with one output element of the planetaryreduction gear set (VS), external disc carrier of the first clutch (A)is connected with one element of the third planetary gear set (RS3), anexternal disc carrier of the third clutch (E) is connected with oneinput element of the planetary reduction gear set (VS) and with thedrive shaft (AN), the internal disc carrier of the third clutch (E) isrespectively connected with one element of the second planetary gear set(RS2) and of the third planetary gear set (RS3), the second brake (D) isconnected with one element of the second planetary gear set (RS2), thehousing is connected with one supporting element of the planetaryreduction gear set (VS) and the driven shaft (AB) is connected with oneelement of the second planetary gear set (RS2).
 11. The multi-stagetransmission according to claim 10, wherein the planetary reduction gearset (VS), observed radially, is substantially situated beneath thesecond clutch (B).
 12. The multi-stage transmission according to claim10, wherein that the third clutch (E), observed radially, issubstantially situated beneath the first dutch (A).
 13. The multi-stagetransmission according to claim 10, wherein at least the second clutch(B) has one servo device with a dynamic pressure compensation.
 14. Themulti-stage transmission according to claim 10, wherein a first ringgear (H1)is provided as an input element of the planetary reduction gearset (VS).
 15. The multi-stage transmission according to claim 10,wherein a first spider (St1) is provided as an output element of theplanetary reduction gear set (VS).
 16. The multi-stage transmissionaccording to claim 10, wherein a first sun gear (S1), which is connectedwith the housing, is provided as a supporting element of the planetaryreduction gear set (VS).
 17. The multi-stage transmission according toclaim 10, wherein the second planetary gear set (RS2) and the thirdplanetary gear set (RS3) are both designed as Ravigneaux gear sets. 18.The multi-stage transmission according to claim 10, wherein themulti-stage transmission can implement six forward gears and one reversegear.